Extensive clinical experience with Sandimmune in prophylaxis of organ rejection following allogenic transplantation has amassed since United States FDA approval in 1983. The profile of adverse events with this drug is well developed, however, the inital evaluation of the bioequivalence was performed in normal subjects. The oral bioavailability of cyclosporine was shown to be different in transplant patients, mainly due to drug absorption characteristics. Also isolated reports have underlined some pharmacokinetic difference between the two oral formulations of cyclosporine when renal transplant recipients were converted from the oral solution to capsules. Therefore, this study evaluates the bioequivalence of Sandimmune oral solution compared to Sandimmune soft gelatin capsules in renal transplant patients with poor absorption of cyclosporine.